A lot of people like the thule ones (used to be Chariot). They are good, but they tend to have very limited storage space, once the child is bigger. I prefer the croozer ones for that reason. Burley are also highly thought of. If you are likely to use it in pushchair mode, the thule/chariot ones work extremely well as a pushchair or running buggy - we went on a march with the lad in it when he was way past normal pushchair size (about 6, I think) and it was still easy to push, even compared to normal pushchairs. The cheaper ones tend to be heavier and less effective as a pushchair for regular use. If you aren't likely to swap between modes very often, one of the cheaper ones may well be fine, although I would avoid very cheep ones as they can be rather flimsy. If you are on Facebook, there is a very knowledgeable family cycling UK page. It is possible to get a baby/toddler insert which helps support a smaller child.
